The following invention relates in general to information storage systems and in particular to aggregating shelf IDs in a fiber channel storage loop.
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates in formation or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Fiber Channel or FC systems are a particular type of information handling system. Fiber Channel is an integrated set of standards for flexible high-speed serial data transfer. A particular topology is a Fiber Channel Arbitrated Loop (FC-AL) (which may also be referred to herein as a Fiber Channel Loop or FC Loop). Current Fiber Channel Loops may have multiple subsystems or enclosures (which may also be referred to as disk enclosures, or data storage modules) with up to 126 connected devices. Note, however, that many more devices may theoretically be attached to the Fiber Channel fabric.
Most fiber channel storage sub systems are so called disk enclosures, with disk drives divided across a number of chassis. These chassis are often connected to one another and then to storage processors. Because the disk drives are connected in a loop fashion, it is a requirement that each disk drive have a unique identifier. In current fiber channel storage systems, this identification is a combination of the disk drive ID within the chassis in conjunction with the so-called shelf ID of the chassis.
Current direct attached fiber channel sub systems allow for a maximum of eight shelf IDs with 16 devices per shelf ID. This results in up to 128 possible devices on a fiber channel storage loop. Of these 128 devices, two devices per shelf ID are typically claimed by SCSI protocol overhead, resulting in a maximum configuration of 112 physical drives connected to a single direct attached fiber channel sub system.
Each fiber channel enclosure, whether it is a traditional multi drive storage enclosure (such as the power vault 650F or power vault 660F sold by Dell Computer Corporation) or a modular data storage module, is assigned one of the possible eight unique shelf IDs. Since modular storage systems typically contain between three to six drives (considerably less than the maximum of 15 physical drives) the remainder of the drive IDs which could be assigned to the shelf ID will be forfeited, reducing the total number of physical drives that can be connected to the FC Arbitrated Loop. By reducing the total number of physical drives that can be connected to the FC-AL, the FC Loop is not fully utilized and may hamper the management of storage devices within the FC Loop.
Therefore a need has arisen for a system and method for managing device shelf IDs in a fiber channel storage loop.
A further need has arisen for a system and method for aggregating shelf IDs in a fiber channel storage loop to maximize the number of devices connected to the fiber channel storage loop.
In accordance with teachings of the present disclosure a system and method are described for managing shelf IDs in a fiber channel storage loop that overcomes or eliminates problems associated with prior addressing methods.
In one aspect a modular fiber channel information handling system is disclosed that includes a storage processor, a storage processor, and multiple associated fiber channel data storage enclosures. The storage processor, storage processor, and the fiber channel data storage enclosures are connected by a fiber channel storage loop. The storage processor includes an identification engine operable to assign device addresses to the associated storage devices. The fiber channel data storage enclosures may include one or more modular data storage enclosures that have a fractional shelf width. The data storage enclosures include a shelf ID selector. The modular data storage enclosures, include an associated shelf ID selector and an aggregation selector. The storage processor also has an aggregation engine that is able to selectively aggregate the shelf IDs of data storage enclosures that have been selected to be aggregated. More particularly, the aggregation engine may check the status of the aggregation selector of each associated data storage module and may also determine whether an aggregation error condition exists.
In another aspect, a method for aggregating shelf IDs of data storage modules of a fiber channel storage loop includes providing multiple data storage modules where each data storage module includes an aggregation selector. The method also includes providing a storage processor that has an identification engine and an aggregation engine and associating the storage processor and the storage modules via a fiber channel storage loop.
The present disclosure includes a number of important technical advantages. One technical advantage is providing a storage processor that includes an aggregation control module. The aggregation control module advantageously allows the device and shelf IDs of associated data storage modules to be managed. Another important technical advantage is providing an aggregation selector on each data storage module. Providing the aggregation selector allows each data storage module to be selected for aggregation. Additional advantages are described in the figures, description and claims.